Direction finding system



Jan. 30, 1951 L. G. FISCHER 2,539,413

A'DIRECTION FINDING SYSTEM Filed April 6, 1946 2 Sheets-Sheet l @@gz u10 -f A .Sz/PH y 1 ical/P1. se 29 *1 -1.2.! 11 #56E/VER car/pue 13/1;`14 I IN V EN TOR.

ATT OHNE' Y 2 Sheets-Sheet L. G. FISCHER DIRECTION FINDNG SYSTEM Jan.30, 1951 Filed April 6, 1946 atenteci jan. 30,

PATNT' y iapiiiiotitioii April t, 1946,*soria1'ito-tt This inviati-tioniflate's to Jii'iootioii fiiiolers ana *nio-ro particularly to 'motlioos'ao apparatus "for ayiiohroriizing'trio switoliiiig the direction midjerindicator where the l'o'oiii-plete rotation of a -zlirecit'iv'oatltoiilias which are arranged to sweep A r stil-l furtherA'filiiiaotgis to provide 1a siifioiooitation for 'dire-otioaitiiiiigapparatus 'a'a botween 'the aiit'oniia 'and oaiillosoopo vswoop whioliis aim-p1v ao minimizes tlimoultio-a of operation.

ptit-woon the sweep -fo the a'iiteima anja of the iniiioatlngoscilloscope' beam will be olot'aineii fot taouindopeudoitt -aiitimaarray; This iiia'y be iii quadratura phaseto 'oo 1a. 3 illustratiaplii'oally the signal wwei var'ioiiao'ifoiiits of 'appli'- cantsafraljtgonient resulting from the switching corresponding 4to the"sect'i 'Sctni'ng of 'the "am"- .t'n'a sysltelil motors andsimultaneously to switching circuit 9 over a line 23. Thus, theswitching circuit acts successively to couple antennas I, 2, 3 and 4 toreceiver II during a period corresponding to the angular sweeps of theseparate directive antennas. A power supply source 24 furnishes power tothe switching circuit 9, receiver II and to the control circuit 25 ofthe oscilloscope indicator I5.

Each of the motors 20 has associated therewith a sine wave generator 26to be driven thereby. The generators 26 are each provided with tworectiers 21 and 28 to produce a positive and negative full wave rectiedsine wave, two of which are applied in phase quadrature to the propervertical and horizontal deflection plates I3, III, 29 and 30 of theoscilloscope I5 after having been subjected to a selection as toquadrants in a sweept quadrant selector 3I. The selector 3l iscontrolled in its operation from the switching circuit 9. This selectormay be of any known electrical type, which shall operate to feedsuccessively to the pairs of deilecting electrodes of the oscilloscopethe proper combination of positive and negative voltages derived fromthe rectification, as described below for the successive quadrants, eachtime the control for such quadrant is impressed on the selector fromswitching device 9. It is, of course, possible to select quadrantseither mechanically or electrically.

In Fig. 2, there has been illustrated the type and relationship of twosweep controlling rectified sine waves which, in the instanceillustrated, are used to produce a quarter circle beam pattern in thefourth, or upper left quadrant by the use of a positive vertical and anegative horizontal rectied sine wave, which are in quadrature phase.Successive quadrants on the oscilloscope may be chosen by applyingplus-plus, minus-plus, minus-minus, and plus-minus voltages to thedeecting plates. These voltages, varying in value according to theinstantaneous values of the sine wave, from Awhich they are derived, incombination provide a resultant for causing beam movement'. Therespective quadrants and the associated voltage polarities areindicated-in Fig. 2 and correspond to the respective polarities of therectied waves indicated in the various rectiers 21 and 28 in Fig. 1.

Thus for a particular cycle of operation, the

supply 22 successively switches the outputs of:

each goniometer to the receiver II by means of switching circuit 9. Thiscircuit may comprise for example, a continuous stepping relay or motor.This switching function is shown schematically in Fig. 3, wherein thenumerals I, II, III, IV correspond to the four periods of a switchingcycle and also the successive coupling of the goniometer correspondingto sectors Ia, 2a., 3a and 4a. The output of the receiver for anexemplary case where a signal is being received from a direction betweenquadrants 2a and 3a is shown at a of Fig. 3. This null type of radiationpattern is more completely disclosed in the copending application#553,598 previously mentioned. The output of each generator 26 comprisesa sine wave as shown at b. Each of the sine waves are full waverectified in 21, and phase advanced 90 in 35 and full wave rectified in28 to provide respective full wave rectified sine and cosine outputs asshown in c. Each of these rectied outputs is applied to selector 3l tobe sequentially applied to thehhorizontal or vertical deflectionelements in synchronism with the operation of circuit 9 andy hence undercontrol of supply 22. Assuming .for simplicity that all the motors aresynchronized, then all of the gener-l ator sine waves will be in phase,and hence all the rectined sine waves willbe in phase and similarly therectified cosine waves. The selector 3l which may comprise thearrangement shown in Fig. 4, switches rectied sine and cosine wavesunder control of circuit 9 by means of coupling 36 and hence undercontrol of 22 to the deection elements of the indicator I5. Thus during-the rst period I, the rectied generator sine output corresponding tosector 4a is applied to plate 29 through coupler 34 and the rectifiedcosine output through coupler 33 to plate III, plates I3 and 30 beinggrounded through couplers 33 and 34 respectively as shown in Fig. 4.This method of coupling is disclosed in greater detail in the copendingapplication #553,562 below mentioned. During period II, the rectied sineoutput corresponding to sector Ia is applied to 29 and the rectifiedcosine output to I3, plates I4 and 30 being grounded. Similarly forperiod III and IV the rectied outputs are applied to the deection platesas indicated at d. The circular trace produced on the screen of theindicator as shown at e is broken up into the sectors as shown by I--IV.

Although the operation of the direction finding system and theindividual antenna array and associated oscilloscope sweeps is apparentfrom inspection of the drawings, it is well to point out that, as thegoniometers, the operationof which has been explained in detail in theabove-identified application by Busignies, are operated by the motors 20they cause a 90 directive sweep of the associated antenna arrays, asalso disclosed by Nathan Marchand in his copending application, SerialNo. 553,562, filed September 11, 1944,. The goniometers may becontinuously operated for all four of the antennas and are preferablyarranged so that the sweep of the next successive antenna will beginsubstantially at the same point where the corresponding sweep of thenext preceding antenna has been discontinued. Because of the switchingcircuit 9, each antenna will be eiective to pass energy to receiver I Ionly during the time when it is sweeping throughone arc. Other anglesmay, of course, beswept if the number of antennas is more or less thanthe four illustrated. The switching circuit, which may, as alreadypointed out, be-electrically or mechanically operated, not only controlsthe passage of energy to the receiver in accordance with the successiveantenna sweeps, but also controls the quadrant selector 3| so that therectified sine waves having the proper polarities and corresponding tothe generator associated with the antenna from which energy is beingreceived are being applied to the deflectors of the oscilloscope. theantenna and the indicator sweeps can be obtained for each independentantenna array.i Further, since each array supplies its own sweep, noalignment is necessary between individual units and the speed of thesweeps need not be identical. The sweeps may be made frequent enough togive the impression of a continuous full 4circle sweep.

While the above is a-description of the prin,- ciples of this inventionin connection with specc apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationonvthe scope of this invention as set forth in the objects.

1. A direction nder for indicating the direction of transmittingstations within a given arc, comprising means for producing a pluralityof Thus, perfect synchronization between .v

, fans-ciers directive .radiant Yenergy receiving gpatterns, for:sweeping Athe rzdirective 'eiect rof said ipatterns successively .fthru,givenv contiguous 'mieles -to Ndefine =.together said given arc, meansion producing :in :synchronism :with .the :respecftive :sweeps .of -eachApattern thru its..ang1es\.a .corresponding 'indicator 4tracefeachcorrespond'- aing. .to respective :angular portions of said farc. :an:mea-ns lfor -applying'received energy ffrom said f directive Patterns:to lcombine with .said `.laaees to 'produce deections vv.off-saidtraces toI "in- '.dicateathe cdirectivecposition 'of transmittingstations within said arc.

12g .Afdirectioninnder system comprising means 'for producing aplurality of directive radiant energy receiiiinfg.` ipatternspxmeanslforsweeping the .directiveeiect .of said...pa.ttern s successively 'thrugiven contiguous 'angles to .denne together said given alii?, anindicator, means for producing in synchronism with the sweepr'each ofsaid patternszrespectively an indicator trace eachfoore asnondingto therespective angular pcrtion'snf 'said arc, a receiver.. meanswforsuccessively .coupling said pattern producing ymeans to lsaidfrcen :and'means for applying the output of said .receiver to 'said indicator .to`4.produce za. .ide- 'nection of 'said trace inV response to receivedsignals.

' .13, A di-rectionnnder systemv for indicatingtthe direction oftransmitting stations within a given arc, comprising a plurality ofdirectional antennas each having a given directional characteristic,means for controlling said directional antennas to successively sweepsaid directional characteristic through contiguous portions of saidgiven arc, an indicator, means for providing a series of independenttraces on said indicator corresponding to said respective arc portions,means for synchronizing traces with the respective sweeps of saidantennas over the corresponding given arc positions, a receiver meansfor successively coupling said antennas to said receiver during theperiods of said successive sweeps, means for bringing intocorrespondence said indicator sweep means with the respective sweeps ofsaid antennas, and means for applying the output of said receiver tosaid indicator to produce a deection of said indicator sweeps inresponse to received signals.

4. A direction nder system comprising a plurality of unidirectionalantennas each having a single directional characteristic, means `:forcontrolling said antennas to successively sweep the directionalcharacteristics of successive v'an-- tennas through predetermined anglesto provide a resultant sweep through an angle substantially equal to thesum of said predetermined angles, a receiver circuit having an input andanoutput, means for cyclically coupling said antennas in succession tosaid receiver in timed relation with respect to said successive sweeps,an indicator, circuit means for providing an indicating trace on saidindicator one corresponding to each of said antennas, means forestablishing correspondence between the occurrence of said traces andthe sweeping of corresponding predetermined angles by the respectiveantennas, and means for applying the output energy from said receiver tosaid indicator to produce deiiections of said trace lines in response tosaid output energy.

5. A direction finder system comprising a plurality of directiveantennas each arranged to produce radiation patterns having a singledirective characteristic, control means for sweeping 7s said.chararcteristicsy :through predetermined angles :such .sthat they'sdeiine together a fsubstan tiallycfillwarc, receiver means; switchingmeans `ttor ecyclicaliy- :coupling successive `ones Iof* said antennas.tn :said "receiver :means 'for a period corresponding .tothe .time :the:corresponding terme iis ibeing'lsweptxthrough said `predeterm-in'edangle-.1an"oscilloscope:indicator,.means for swee'pi ving the-beamof-:said oscilloscope over predetermined sweep paths in correspondencewith-fthe sweepingbyisaidantennas of respective predeter-.anirredlangles :respectzto time and position on :indicatonfandmeans forcoupling said `vre. reiner means 'to said oscilloscope to 'provideydeectionsioffsaid sweep .beam in' .response .to received signals.. v

- direction 'ndervsystem comprising 'a vplurality-Lof. :directive"antennas 'arranged .abouti-g, giuenapoint freach Shaving 'its'directive action putwardly ."iru'mA `said"point, control means vforv'controlling fthe-directive action of each of saidanterm'astossweepitthrough a given angle whereby saidantennas-coveraresultant 360 angle vsweep about :said point, synchronous drive means`for driving .said control means, an indicating oscil`-' lescope ihavingan indicating beam, means for moving 'said beam to produce trace linesin synchronismnwithand-corresponding in number and timing .to .the sweepof each of said antennas:

through a respective given angle, a receiver circuit having its outputcircuit coupled to said indicator to produce deflections of said beameffective on said traces in response to received signals, and aswitching circuit for successively coupling said antennas to saidreceiver and said beam moving means for a period substantially equal tothe time the corresponding directive action is being swept through itsgiven angle.

7. A direction finder according to claim 6, in which said beam movingmeans includes a source of sinusoidal voltage for providing a base sweepfor said beam moving means associated with each of said synchronousdrive means.

8. A direction finder system for indicating the direction oftransmitting stations within a given arc, comprising a plurality ofdirective antennas arranged about a given point each having itsdirective action outwardly from said point, control means forcontrolling the directive action of each of said antennas to sweep itthrough a given angle whereby said antennas cover a resultant given arcsweep about said point, synchronous drive means for driving said controlmeans for veach of said antennas, an indicating oscilloscope i having anindicating beam, means for producing a time base trace for said beamcorresponding to each of said given angles operatively associated withsaid drive means, a receiver circuit having its output circuit coupledto said indicator to produce deflections of said beam eiective on saidtraces in response to received signals, a switching circuit forsuccessively coupling said antennas to said receiver for a periodsusbtantially equal to the time the corresponding directive action isbeing swept through its given angle, and means for selecting the properposition for the beam line trace on the indicator corresponding to thegiven angle being swept by said directive action operatively controlledby said switching circuit.

9. A system according to claim 8, in which said given arc comprises 360,said antennas comprise four in number arranged to sweep each, and saidtime base means is arranged to produce four separate corresponding 90traces.

l0. .A system according to claim d, in. which :accadde said time baseproducing means comprise a sine wave generator, one for each of saidantennas driven by said drive means and a combination of full waverectiers for each of said generators having polarities significant inrespect to the relation of each of the traces to the correspondingrelative angular portion of said given angle swept by the correspondingantenna, whereby the position of a trace is made to relate to said givenangle.

11. A direction nder system for indicating the direction of transmittingstations within a given arc, comprising four directive antennas arrangedabout a given point each having its directive action outwardly from saidpoint, individual control means for controlling the directive action ofeach of said antennas to sweep it through an angle of 90 whereby saidantennas cover a resultant 360 arc sweep about said point, a synchronousmotor for driving said control means for each of said antennas, anindicating oscilloscope having an indicating beam, a sine wave generatorfor producing a quarter circle time base trace for said beam, onegenerator being associated with each of said motors, a receiver circuithaving its output circuit coupled to said indicator to producedeflections 'of said beam effective on said traces in response toreceived signals, a switching circuit for successively coupling saidantennas to said receiver for a period substantially equal to the timethe corresponding direc'- tive action is being swept through therespective angle, double full wave rectifier means for each generatorhaving opposite polarities cycli'- cally` switched by said switchingcircuit to de'- i'lect said indicating beam into the quadrantcorresponding to the respective directive action being swept, and meansfor selecting the proper position for the beam line trace correspondingto the given angle being swept by said directive action operativelycontrolled by said switching circuit.

- LAURIN G. FISCHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Labin Apr. 29, 1947

